1. Field of the Invention
The present invention relates generally to a vibration motor, and more particularly to an eccentric rotor of the vibration motor.
2. Description of Related Art
Mechanical vibrations are required for many different applications. Such as vibrations for material pulverization and selection in industrial use, vibration for home massage machines, and silent notification of incoming calls and messages for mobile phones, are but a few examples of mechanical vibration applications.
There are various methods that can be used to produce mechanical vibrations. One method involves the use of electric motors. A conventional type of vibration motor includes a casing receiving a stator therein, a shaft connected with the stator, and a rotor being rotatably disposed around the shaft. The rotor includes a bearing mounted around the shaft and an eccentric weight attached to the bearing. Vibration is produced by the rotation of the rotor as a result of the eccentric weight attached to the rotor. However, the eccentric weight is usually made of copper. A density of the copper is about 8.9 g/cm3, which is too small to enable the eccentric weight to generate a highly satisfied vibration effect.